#sleep and wakefulness

[the-banks-of-lethe]

Circadian Rhythm: The Basics

As voted on on Wednesday, I'll be covering the basics of the circadian rhythm! When I say basics, I mean the basics, this isn't a deep dive by any means and really just scratches the surface of it. Feel free to add anything on or go and research more yourself if you find it interesting. I might do a deep dive once I get more knowledgable on the subject, but for now, this is it!

[My writing will be in blue for ease of recognising what is my writing and what is quoted. Quoted things will have their links attached.]

Dictionary definition: Circadian rhythm (sir-KAY-dee-un RIH-thum). The natural cycle of physical, mental, and behavior changes that the body goes through in a 24-hour cycle.

"Circadian rhythms are the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle. Light and dark have the biggest influence on circadian rhythms, but food intake, stress, physical activity, social environment, and temperature also affect them. Most living things have circadian rhythms, including animals, plants, and microorganisms. In humans, nearly every tissue and organ has its own circadian rhythm, and collectively they are tuned to the daily cycle of day and night.

Circadian rhythms influence important functions in the human body, such as:

Sleep patterns

Hormone release

Appetite and digestion

Temperature" National Institue of General Medical Sciences

Basically, your circadian rhythm is your biological time clock*. Telling your body when to do stuff based on your environmental factors and habits; also called a Zeitgeber (German, literally translating to 'time giver', also translated to 'synchronizer'). A Zeitgeber is anything that resets the bio-time-clock. Most commonly its the sun, but it can really be anything that is consistently reoccuring enough in your scheduele for your body to recognize it as a signal of 24hrs passing. This could be food, excercise, social interactions, etc. Humans are creatures of habit, and our brain reflects that.

*Technically, it's not. I know, sorry. But it is at the same time. The suprachiasmatic nucleus (SCN) is your bio-time-clock; but the SCN is what triggers your circadian rhythm, not just for sleep but for all the other things affected by it; like body temperature, which rises during the day to keep you awake, and drops at night.

My personal favourite experiment / study on the circadian rhythm is the Richardson & Kleitman Mammoth Cave Experiment, 1938.

^^ short video from 1938, subtitles are available.

"Normal sleep--wakefulness cycles operate on a seven day, 24 hour cycle; Kleitman wanted to adjust himself and graduate student Richardson to a six day, 28 hour week."

"Kleitman and Richardson spent 32 days in the cave with a strict schedule of sleeping for 9 hours, working for 10, and 9 hours of leisure time. The absence of light and noise and a constant temperature made for a great experimental environment."

"The goal of their experiment was to determine if humans had an ingrained 24 hour cycle or if we can adjust our circadian rhythm. Measuring changes in body temperature shows a range of 1–2°F change with the highest value in the afternoon and the lowest in the early morning. This curve is not seen in infants, but develops as children adapt to rest-wakefulness cycle of 24 hours."

"It is known that the body temperature curve can be shifted any number of hours, as when a person moves from the United States to China, or it can be completely inverted as when a person regularly stays up at night and sleeps in the day-time [sic]. In either case, however, the duration of the cycle remains unchanged, namely, 24 hours. It is our purpose to find how easy or how difficult it is for a grown up individual to change his body temperature curve from a 24-hour to a 21-hour or 28-hour cycle."

^^ above four (4) paragraphs and video from here

After the experiment concluded, Kleitman wrote and published a study based on their findings called 'Sleep and Wakefulness'.

^^ you can borrow the book for free online, you kind find lots of books / videos / texts / media on here, you just need to sign up <33 (The Internet Archive)

"Nathaniel Kleitman, who died on August 13, 1999 at the age of 104, can be properly described as “the father of modern sleep research”. His claim on this title stems from both his scholarly integration of the work in the field and his own research. His 1939 compendium of prior work on sleep and wakefulness, revised in 1963 (18), includes thoughts on sleep ranging from Aristotle and other ancient thinkers to 20th century pioneers such as Pieron, Hess, Nauta and Kleitman’s contemporaries. The explosive recent growth of the field guarantees that this will be the last such comprehensive, research oriented integration of the literature in sleep research. In the introduction to the 1939 edition, Kleitman apologizes that his reading abilities are “limited to French, German, Italian and Russian” (and English). However, despite this “handicap” he critically integrates 4337 references covering sleep, circadian rhythms, sleep disorders, hibernation and theories of sleep function." - A Tribute to Nathaniel Kleitman

Okay, so not as short as I originally expected, but I could've written more, so yall are lucky I decided to cut it off there. If you have any questions or noticed that I got something wrong, or would ilike to add anything - please feel free!!

I have gotten a lot of what I know of sleep from an amazing amazing book called 'Why We Sleep' - by Matthew Walker. I'm only part way through it but I love it so much, and can definitely see myself buying a copy in the future. Here's a link to his website: https://www.sleepdiplomat.com/ [I only just found his website and omg I didn't know he had a podcast, I know what I'm going to be listening toooo]

Anyway, I hope this has been informative and is a good starter to get you into the science of sleep! I love Hypnos and his realm.. and I hope I can spread further information on him and his domains to others!

Χαίρε Hypnos, and sweet dreams!

[overcaffeinated-aro]

ok not to be that guy but like. labor rights and working class rights can coexist with 24h services and late amenities. its certainly hard to do so without worker exploitation in this political and social environment, it’s not a conflict likely to resolve overnight. but 24h services are important and especially valuable to those of us that are disabled or are on a different circadian rhythm. in fact more professional, health, and government services should be available or at least possible to work on asynchronously (if applicable) during late or odd hours, while workers also get sufficient pay for their labor and proper consistent scheduling. this would be much easier on the workers with night schedules if the entire professional world didn’t grind to a halt at 5pmEST

[taffywabbit]

they should invent a new type of "staying in bed for 2-3 hours after you wake up repeatedly opening and closing apps on your phone" where it makes you feel awesome and energized and emotionally fulfilled

[lunaliart]

nap time

[reaandull]

exiting with a bang

[sillywillyco]

eepy

[shouyuus]

lmao why do i feel like bakugo would be a sleep talker, and like a loud one -- none of that mumbling stuff that izuku sometimes does but like, yaps in his sleep, just little snippets --

"-- don't you dare --"

"-- nerd --"

"-- just g'na blow it up --"

"-- so lame, what're you even --"

"-- keep em safe --"

"-- get down! get down!"

"... love... don't go --"

"... love you --"

you greet him in the morning with a smile, a kiss, and a cup of coffee.

"you were talking in your sleep last night," you say, casual, peaking at him over the rim of your own steaming coffee mug. the frothed milk is sweet on your tongue.

katsuki flushes a bright red, his eyes cutting away.

"yeah, well... hope i didn't say anything weird or embarrassing."

you laugh, "no, nothing embarrassing. you were yelling for a bit --"

"oi --"

you wave him off with a grin, "but..." your eyes twinkle, "then you said some... some pretty sweet stuff so..."

at this, katsuki goes an even more impossible shade of red as he mumbles into his coffee cup --

"well yeah... at first i think i was... fightin' something but then... then i started dreaming 'bout --" he clears his throat, his scowl digging ever deeper between his brows, "'bout you."

[pudgybun]

pudgy pic for tumblr ♡ (> w <)

[irunaki]

another mission nailed

[darkrootmushies]

Ew ew ew ew ugly

[summertimenoir]

Title cards from some classic noir movies (1940 - 1952)

[mobius-m-mobius]

I'm gonna be the man who's comin' home with you But I would walk five hundred miles -

The Proclaimers – I'm Gonna Be (500 Miles) ft. David Tennant Doctor Who BTS (2009) // BAFTAs (2025) edition

[dollyfetti]

katsuki loves your lip balm.

he’ll buy you as many different flavors and brands as you’d like, just to see the shimmery glisten it brings upon your lips. he especially loves seeing you when you’re all ready for bed, bonnet/scrunchie in your hair, your face all moistened and soft, and your lips adorably glossy.

he loves grabbing your chin and smushing his lips onto yours, smearing the product everywhere on your chin and his. he pulls back with the dorkiest grin that spreads even wider when you whine about having to reapply and your chin being all sticky.

he loves it so much that he’ll spend hundreds of dollars on it per month just to see it on you.

[desertowlet]

When it comes to studying aboard the Tulpar, I'd like to think Anya assembles the ultimate study playlists and is quite proud of them, (they mainly consist of nature documentary scores such as Blue Planet II and Frozen Planet II) 💙💙💙

Bonus:

[sugurusladyknightt]

➺ suguru x gn!reader

if you set a timer to nap suguru will absolutely sabotage you.

let me set the scene. you're getting comfortable laying on his chest his arms secured around you and your eyes closing with a content hum and then suddenly your like 'oh hold on' and grab your phone to set a timer then promptly explain that you have something to do so you don't wanna oversleep during your nap and end up losing time.

but you're so tired, he knows a short nap won't be enough rest though, he says nothing. you get comfortable on his chest again, your cheeks smooshed against his skin and doze off shortly after thanks to the soothing hand at your back and head and the warmth of his skin. when you're asleep this man will fully just grab your phone and cancel the timer, that way, you get all the rest your body needs undisturbed and wake up when your ready.

if it's assignments or notes or anything really that he can do for you, then he will do it for you. taking neat concise notes for you, or finishing up your research paper. no this is not a violation of academic integrity because you are his baby. you are his person and he is yours so to anyone else you may as well be the same person, and anyway he isn't plagiarizing or cheating. suguru does a really good job actually.

when you wake up later, dry eyes slowly blinking away the sleep and readjusting to the light. the skin of your cheek turned pink from how long it's been resting against him softly greeting him in a small raspy voice. when you wake up enough to realize the timer hadn't gone off and reach over to your phone to check the time, the sleep leaves you so fast. you're frenzied, panicked, confused. as if you've been splashed with cold water. suddenly awake and upset about all the time you had wasted what about the timer? how are you supposed to finish everything now?? only for you to find everything done and neatly organized for you to look over, anything with a tight deadline? already sent in.

oh. well.. now that you have nothing that urgently needs your attention (besides him) you can lay back down on his chest and continue where you left off 🙂‍↕️

[tidalst]

My @aftgexchange for @thechaoscryptid! Sorry this is late, but I hope you like it!

prompts: learning to accept intimacy // there was only one bed